Auxiliary contact interlock for preventing electrical discontinuity between main bridging contact and fixed contacts

ABSTRACT

An auxiliary contact interlock for use with an electromagnetic contactor having an operating arm, the interlock being characterized by stationary and movable contacts within a housing. The movable contacts of which are mounted on a movable contact carrier, each movable contact comprising a contact button and an adjacent flexible contact biased toward the corresponding stationary contact and engaging the same before or after the contact buttons when the movable contact carrier is moved in close proximity to or from the closed position with the stationary contact.

United States Patent Richards et al. July 1, 1975 [54] AUXILIARY CONTACT INTERLOCK FOR 2,429069 10/1947 Murray .1 200/146 R PREVENTING ELECTRICAL 2.662.94l 12/1953 Fisher ZOO/I65 X 3,l76,l09 3/1965 Wodtke 1 1 200/288 DISCONTINUITY BETWEEN 3.272941 9/1966 Kobryner 200/!46 R x BRIDGING CONTACT AND FIXED 3,600,542 8/197] Richter 200/288 CONTACTS (75] Inventors: Edward L. Richards, Aliquippa; Primary Examiner james R Scott g' f Camem Beaver both of Attorney, Agent or Firm-J. P1 Johns [73] Assignee: Westinghouse Electric Corp.,

Pittsburgh, Pa. 57 ABSTRACT 22 F] d: M 14,1974 l I 6 M An auxiliary contact interlock for use with an electro- PP 451,249 magnetic contactor having an operating arm, the interlock being characterized by stationary and movable LS. CL 200 2 5. 2 contacts within a hOUSll'lg. The movable COl'ltaCiS 0f 200/256 335/193 which are mounted on a movable contact carrier, each [51] In. CL I I HOIh 3/60 movable contact comprising a contact button and an [58] Field R adjacent flexible contact biased toward the corre 200/238 243 250 5 6 sponding stationary contact and engaging the same be- 6 fore or after the contact buttons when the movable contact carrier is moved in close proximity to or from [56] Reierences and the closed position with the stationary contact.

UNITED STATES PATENTS 4 Claims, 8 Drawing Figures 2,352,550 6/1944 Joseph 1. 200/146 R X PATENTEIJ L 1 SHEET FIGZ PATENTEDJUL 1 SHEEI FIGZ) FIGS FIGS

AUXILIARY CONTACT INTERLOCK FOR PREVENTING ELECTRICAL DISCONTINUITY BETWEEN MAIN BRIDGING CONTACT AND FIXED CONTACTS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to electromagnetic contactors and more particularly to auxiliary contact assemblies or interlocks associated therewith.

2. Description of the Prior Art Auxiliary contact assemblies or interlocks have been used with electromagnetically actuated contactors for some time. For example, US. Pat. No. 2,546,00l. issued Mar. 20, 1951 discloses an electrical interlock for use with an electromagnetic contactor which interlock includes contacts which are useful either in the nor mally open or normally closed positions. Although spring biasing means are provided for maintaining the contacts closed, it has been found that where the contactor is used on or near high impact shock equipment the contact may separate momentarily and cause a Clis continuity of electric service.

SUMMARY OF THE INVENTION In accordance with this invention it has been found that the foregoing problem may be overcome by providing an interlock comprising a housing, stationary and movable contacts within the housing, a movable structure movable as a unit and comprising a movable contact carrier, each movable contact comprising a contact button and an adjacent resilient contact. each resilient contact being biased to a position between and adjacent to the contact button and the stationary contact, whereupon movement of the movable contact to the closed position with the stationary contact the resilient contact engages the stationary contact before the contact button, and whereupon movement of movable contact to the open position the resilient contact leaves the stationary contact after the contact button.

The advantage of the interlock of the present invention is that by providing resilient contacts in association with each contact button any momentary separation of the movable contact button from the stationary contact does not result in a discontinuity of service. because the associated resilient contacts maintain engagement with the stationary contacts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side view of the auxiliary contact interlock mounted in place on an electromagnetic contactor, and showing the interlock in the normally open position;

FIG. 2 is an enlarged view of the auxiliary contact in terlock in the normally open position;

FIG. 3 is a side view of the interlock in the normally closed position and inverted for mounting in place in the position shown in FIG, I;

FIG. 4 is a vertical sectional view taken on the lines IVIV of FIG. 2;

FIG. 5 is a vertical sectional view taken on the lines V-V of FIG, 3;

FIG. 6 is an enlarged side view of the movable contact carrier;

FIG. 7 is a bottom plan view taken on the lines VII- -VII of FIG. 6; and

FIG. 8 is a bottom plan view of another embodiment of the movable contact carrier.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. I an electromagnetic contactor is generally indicated at III which is not shown in its entirety and includes among other things an arm 12 and an auxiliary switch or contact interlock [4. The contactor l0 and the contact interlock I4 are mounted upon a base 16 on which a support 18 is mounted by suitable means such as suitable screws 20.

Generally. when the main contactor 10 is actuated to the closed position. the arm 12 moves in the direction of the arrow 22 to either open or close the auxiliary contact interlock 14 depending upon whether it is nor mally open or closed as set forth below. The purpose of the auxiliary contact interlock is to open or close a circuit through an associated device. such as a signal light or alarm, which may indicate the condition of the electromagnetic contactor 10.

As shown more particularly in FIG. 2 the auxiliary contact interlock 14 comprises a pair of mounting blocks 24 and 26, movable contacts 28, stationary contacts 30, and an operating structure 32 for opening and closing the circuit through the contacts. The blocks 24 and 26 are composed of electrically insulating mate rial. The block 24 is a distinctly U-shaped member and the block 26 is a shallow U-shaped member with parting surfaces 34. The blocks 24 and 26 are secured together by suitable means such as a pair of bolts 36 extending through aligned holes in the blocks. In the assembled position shown in FIG. 2, terminal conductors 38 are held clampingly in place at the areas of the parting surfaces 34 of the blocks 24 and 26. The exterior portions of the conductors 38 are provided with suitable terminal screws 40. The stationary contacts 30 are mounted on the inner portions of the conductors 38 within the blocks 24 and 26.

The operating structure 32 comprises an elongated rod 42, an electrically conductive contact carrier 44, contact spring 46, operating spring 48, and spring stop 50, all of which are located within the blocks 24 and 26. The auxiliary contact interlock 14 is shown in the normally open condition in FIG. 2. In that condition the operating spring 48, being under greater compression than the contact spring 46, holds the moving contacts 28 away from the stationary contacts 30.

The rod 42 extends through a pair of aligned openings 52. 54 in the mounting blocks 24. 26 and is centrally disposed within the operating structure 32. Upper and lower end portions 56 and S8 of the rod extend beyond the top and bottom of the blocks 24, 26 and the upper end portion (FIG. 1) functions with the arm 12 to close the circuit through the contacts 28, 30 against the force of the operating spring 48 when the electromagnetic contactor is actuated to a closed circuit position. The rod 42 includes an enlarged intermediate portion in which a longitudinal opening 59 (FIGS. 7 and 8) having upper and lower ends 60 (FIG. 2) is provided. The contact carrier 44 and the spring stop 50 are slidably mounted in the opening 59 and are normally disposed at opposite ends 60 as shown in FIG. 2. The contact spring 46 disposed between the contact carrier 44 and the spring stop 50 for holding the contacts 28 snugly against the stationary contacts 30 when the rod 42 is moved to the closed position, In that position the assembly of the contact carrier 44. the operating spring 48, and the spring stop 50 move against the pressure of the operating spring 48 which is compressed when the auxiliary contact interlock 14 is in the closed position. When the arm 12 is retracted upwardly, the spring 48 lifts the operating structure 32 up until the outer end portions of the spring stop engage surfaces 62 of the block 24.

As shown in FIG. 3 the auxiliary contact interlock [4 may be used in the normally closed condition by invert ing the position so that the end portions 58 of rod 42 is uppermost to function with the arm 12. In addition, in the normally closed condition the spring stop 50 is adjusted to a position closer to the contact carrier 44 in order to compress the contact spring 46. For that purpose the block 24 is provided with a pair of oppositely disposed shoulders 64 which, as shown in FIGS. 4 and 5, are closer to the conductors 38 than the surfaces 62. More particularly, the shoulders 64 are disposed on the side ofa partition 66 opposite the surfaces 62 and the surfaces, which shoulders and the partition are integral parts of the block 24. Accordingly, by pressing the spring stop 50 toward the contact carrier 44 and compressing the spring 46 until the stop clears the lower ends of the oppositely disposed partition 66 and then rotating the stop to the other side of the partition the spring 46 returns the spring stop to the shoulders 64 as shown in FIG. 5, thereby applying a pressure on the contact spring 46 sufficient to overcome the pressure of the operating spring 48 whereby the contacts 28, 30 are closed.

In accordance with this invention the operating structure 32 comprises resilient contact means, such as flexible metal strips or leaf springs 67 and 68, which are secured by suitable means, such as rivets 70, to the undersurface of the contact carrier 44. The resilient metal strips or leaf springs 67 and 68, being composed of a suitable flexible material, such as beryllium-copper alloy, carries the current only momentarily when the contacts 28 and 30 are separated by vibration or shock. The end portions 72 of the strip 68 are inturned toward the rod 42 to provide a U-shaped end portion. Each end portion 72 is adjacent to the corresponding movable contact 28 and is adapted for engagement with the stationary contacts 30 when the contacts are in the closed position. More particularly, the end portion 72 extend toward the stationary contacts 30 and in the open position of the contacts are closer to the stationary contacts than the movable contacts. The function ofthe flexible end portions 72 is to maintain a continuity ofclectrical contact between the stationary contacts 30 and the contact carrier 44 when the assembly of the electromagnetic contactor l and the auxiliary contact interlock 14 is subjected to substantial shock or vibra tion sufficient to cause the movable contacts 28 to bounce off of or momentarily move away from the corresponding stationary contacts 30. If the movable contacts 28 and the stationary contacts 30 accidently separate slightly due to severe shock or vibration. the contact spring 46 immediately returns the contacts to the closed position, but during the brief time interval that they are separated the end portions 72 remain in contact with the stationary contacts 30.

It is pointed out that although the flexible metal strip 68 is disclosed as being mounted on the same side of the contact carrier 44 as the contacts 28 it may be mounted on the other side. However. by being mounted on the same side as the contacts 28 the strip 68 is subjected to a pressure substantially coextensive with the length of the contact carrier,

Another embodiment of the invention is shown in FIG. 8 in which a flexible metal strip 74 is mounted on the undersurface of the contact carrier 44 by a pair of spaced rivets 76 and is provided with end portions 78 of similar configuration to the end portion 72 but disposed on the same side of the movable contacts 28 as compared with opposite sides as shown for the contacts 72 in FIG. 7.

Accordingly, the auxiliary contact of this invention provides an electrical interlock which is shockproof and better able to maintain continuity of electrical service under conditions of high shock such as on combat vehicles or vessels.

What is claimed is:

1. An auxiliary contact interlock for use with an electromagnetic contactor having an operating arm, the interlock comprising a housing, at least one stationary contact mounted within the housing, a movable structure movable as a unit and including an actuator rod and a movable conductive contact carrier means mounted on the rod, the rod being slidahly mounted in the housing by the operating arm to open and close the contacts when the arm is actuated. each movable contact carrier means having at least one contact button and at least one resilient contact, each resilient contact being located beside and biased to a location between the open and closed positions of the contact button and said stationary contact, the resilient contact having a U-shaped end portion engageable with said stationary contact, upon movement of the movable contact carrier means to the closed position with the stationary contact the resilient contact engages the stationary contact before and at a location adjacent to that of the contact button, and upon movement of the movable contact carrier means to the open position the resilient contact leaves the stationary contact after the contact button.

2. The auxiliary contact interlock of claim 1 in which the resilient contact is a leaf spring mounted on the side of the movable contact carrier means facing said stationary contact.

3. The auxiliary contact interlock of claim 1 in which there are two spaced stationary contacts, the movable contact carrier means includes a conductive bridging Contact carrier extending between a plurality of the stationary contacts, spaced contact buttons on the bridging contact carrier means and aligned with the spaced stationary contacts, the resilient contact being mounted on the bridging contact carrier and having end portions located laterally adjacent to each contact button, and each end portion being nearer the corresponding stationary contact than the corresponding contact button when the movable contact carrier means is in the open position.

4. The auxiliary contact interlock of claim 3 in which the resilient contact is a flexible metal strip attached to the side of the movable contact carrier means facing the stationary contacts. 

1. An auxiliary contact interlock for use with an electromagneTic contactor having an operating arm, the interlock comprising a housing, at least one stationary contact mounted within the housing, a movable structure movable as a unit and including an actuator rod and a movable conductive contact carrier means mounted on the rod, the rod being slidably mounted in the housing by the operating arm to open and close the contacts when the arm is actuated, each movable contact carrier means having at least one contact button and at least one resilient contact, each resilient contact being located beside and biased to a location between the open and closed positions of the contact button and said stationary contact, the resilient contact having a U-shaped end portion engageable with said stationary contact, upon movement of the movable contact carrier means to the closed position with the stationary contact the resilient contact engages the stationary contact before and at a location adjacent to that of the contact button, and upon movement of the movable contact carrier means to the open position the resilient contact leaves the stationary contact after the contact button.
 2. The auxiliary contact interlock of claim 1 in which the resilient contact is a leaf spring mounted on the side of the movable contact carrier means facing said stationary contact.
 3. The auxiliary contact interlock of claim 1 in which there are two spaced stationary contacts, the movable contact carrier means includes a conductive bridging contact carrier extending between a plurality of the stationary contacts, spaced contact buttons on the bridging contact carrier means and aligned with the spaced stationary contacts, the resilient contact being mounted on the bridging contact carrier and having end portions located laterally adjacent to each contact button, and each end portion being nearer the corresponding stationary contact than the corresponding contact button when the movable contact carrier means is in the open position.
 4. The auxiliary contact interlock of claim 3 in which the resilient contact is a flexible metal strip attached to the side of the movable contact carrier means facing the stationary contacts. 